Chaokui Wang

Genome-wide association analysis of Vogt-Koyanagi-Harada syndrome identifies two new susceptibility loci at 1p31.2 and 10q21.3

To identify new genetic risk factors for Vogt-Koyanagi-Harada (VKH) syndrome, we conducted a genome-wide association study of 2,208,258 SNPs in 774 cases and 2,009 controls with follow-up in a collection of 415 cases and 2,006 controls and a further collection of 349 cases and 1,588 controls from a Han Chinese population. We identified three loci associated with VKH syndrome susceptibility (IL23R-C1orf141, rs117633859, Pcombined = 3.42 × 10−21, odds ratio (OR) = 1.82; ADO-ZNF365-EGR2, rs442309, Pcombined = 2.97 × 10−11, OR = 1.37; and HLA-DRB1/DQA1, rs3021304, Pcombined = 1.26 × 10−118, OR = 2.97). The five non-HLA genes were all expressed in human iris tissue. IL23R was also expressed in the ciliary body, and EGR2 was expressed in the ciliary body and choroid. The risk G allele of rs117633859 in the promoter region of IL23R exhibited low transcriptional activation in a cell-based reporter assay and was associated with diminished IL23R mRNA expression in human peripheral blood mononuclear cells.

Decreased microRNA-155 Expression in Ocular Behcet's Disease but Not in Vogt Koyanagi Harada Syndrome

PURPOSE MicroRNAs (miRNAs) have emerged as a class of gene expression regulators involved in immune regulation. In the present study, we investigated the role of miRNA in two uveitis entities: Behcets disease (BD) and Vogt Koyanagi Harada syndrome (VKH). METHODS The expression of five miRNAs was studied in PBMCs, DCs, and CD4(+) T cells from BD patients with active and inactive uveitis, VKH patients with active uveitis, and healthy controls using real-time PCR. MiR-155 mimics and inhibitor were transfected to DCs to evaluate the effect on DC maturation and cytokine production by these cells and CD4(+) T cells. Luciferase reporter assays and Western blotting were performed to identify the target gene of miR-155. RESULTS Only miR-155 expression was significantly decreased in PBMCs and DCs from BD patients with active uveitis and no differences were observed in the miRNA expression in cells from patients with VKH as compared with controls. Overexpression of miR-155 in DCs was shown to inhibit the production of IL-6 and IL-1β, and to promote the expression of IL-10 by these cells. MiR-155 transfected DCs significantly inhibited intracellular IL-17 expression in allogeneic CD4(+) T cells; however, it did not influence the expression of cell surface markers CD80, CD40, CD83, CD86, and HLA-DR. Luciferase reporter assays revealed that TAB2 was a target gene of miR-155, which was confirmed by Western blotting. CONCLUSIONS The present results suggest that miR-155 expression is decreased in active BD but not in VKH patients. Downregulated miR-155 may be involved in BD pathogenesis by targeting TAB2.

Decreased IL-27 expression in association with an increased Th17 response in Vogt-Koyanagi-Harada disease.

PURPOSE IL-27 has emerged as an important regulator of proinflammatory T-cell responses in animal models. We investigated the pathophysiological role of IL-27 in Vogt-Koyanagi-Harada (VKH) disease. METHODS IL-27P28 and EBI3 mRNA expression in peripheral blood mononuclear cells (PBMCs) were assayed by RT-PCR. Cytokines in the serum and supernatants of PBMCs, naïve CD4(+) T cells and DC-T cocultures were assayed by ELISA. Flow cytometry was used to evaluate the frequencies of IL-17-producing CD4(+) T cells. RESULTS The active VKH patients showed a decreased IL-27P28 mRNA expression in PBMCs and lower IL-27 expression in the serum and supernatants of PBMCs, but higher Th17 cells in PBMCs. EBI3 mRNA expression was not different among the groups tested. Stimulation of naïve CD4(+) T cells under Th17 polarizing conditions showed a higher Th17 cell differentiation in active VKH patients. IL-27 significantly inhibited Th17 cell differentiation. IL-27-treated DCs showed a significant inhibition on Th17 differentiation. There was a significant defect in the Tr1 cell induction as measured by IL-10 in active VKH patients. Treatment with corticosteroids and cyclosporine A (CsA) resolved the intraocular inflammation in association with an upregulation of IL-27 and a downregulation of IL-17. In vitro experiments showed that corticosteroids, but not CsA, significantly upregulated the expression of IL-27. CONCLUSIONS The present study suggests that decreased IL-27 expression may result in a higher Th17 in active VKH patients, which may promote the autoimmune response observed in these patients. Manipulation of IL-27 may offer a novel target for treatment of this disease.

IFN-α blocks IL-17 production by peripheral blood mononuclear cells in Behçet's disease

OBJECTIVES IFN-α has been used to treat patients with Behçets disease (BD). Recent studies have implicated the IL-23/Th-17 pathway in the pathogenesis of BD. In this study, we investigated whether IFN-α could affect this pathway. METHODS Peripheral blood mononuclear cells (PBMCs) obtained from patients with active BD and controls were cultured alone or with IFN-α and the levels of IL-17 and IL-10 in the supernatants were measured by ELISA. Similar experiments were performed with isolated CD4(+) T cells from controls. The levels of phosphorylated STAT1 (p-STAT1), p-STAT2, p-STAT3 and p-STAT5 in CD4(+) T cells from controls cultured with or without IFN-α were also evaluated by ELISA. Furthermore, an experiment using anti-IL-10 was performed to examine underlying mechanisms of action of IFN-α. RESULTS Significantly higher levels of IL-17 and IL-10 were observed in the supernatants of PBMCs from BD patients as compared with controls. IFN-α significantly decreased IL-17 production by PBMCs from both patients and controls. On the other hand, IFN-α increased IL-10 production by PBMCs from patients and controls. Similar findings were obtained when using CD4(+) T cells from controls, IFN-α significantly increased p-STAT2 expression in control CD4(+) T cells. Anti-IL-10 antibody was able to neutralize the inhibitory effect of IFN-α on IL-17 by 35% as compared with controls. CONCLUSIONS In vitro experiments showed that IFN-α could inhibit IL-17 expression and increased IL-10 production by PBMCs and CD4(+) T cells. The inhibitory role of IFN-α on IL-17 was partly mediated by IL-10. IFN-α activity was mediated via STAT2 phosphorylation.

Higher expression of Toll-like receptors 2, 3, 4, and 8 in ocular Behcet's disease.

PURPOSE To investigate the role of Toll-like receptors (TLRs) 2, 3, 4, and 8 in the pathogenesis of Behcets disease (BD). METHODS Sixteen patients with active ocular BD and 16 healthy volunteers were included in this study. Total RNA was isolated from PBMCs to determine mRNA levels of TLRs, including TLR2, TLR3, TLR4, and TLR8. Cell surface receptor activity of these TLRs was investigated by FACS analysis. Monocytes and naïve T cells from patients and controls were cultured with or without TLR ligands, such as LPS, PGN, R848, or PolyI:C. Culture supernatants were collected and IL-17, IL-1β, and IL-23 were analyzed by ELISA. RESULTS A markedly higher expression at the mRNA and protein level of TLR2, TLR3, TLR4, and TLR8 was observed in active BD patients as compared with controls. Significantly higher levels of IL-1β and IL-23 were detected in the supernatants of monocytes stimulated with LPS or PGN. A significantly higher level of IL-17 was observed in the supernatants of naïve T cells and monocytes stimulated with LPS or PGN in BD patients as compared with controls. Upon stimulation with R848 or PolyI:C, the levels of IL-17 in the supernatants of naïve T cells and monocytes and IL-23 levels in the supernatants of monocytes were not different between BD patients and controls. CONCLUSIONS A higher expression of TLRs may be involved in the pathogenesis of BD.

Increased Expression of IL-22 Is Associated with Disease Activity in Behcet’s Disease

Objective Interleukin (IL)-22 has been reported to be involved in the development of autoimmune diseases. This study aimed to analyze the expression and potential role of IL-22 in the pathogenesis of Behcet’s disease (BD). Methods The levels of IL-22 in patient sera or supernatants of cultured peripheral blood mononuclear cells (PBMCs) and CD4+T cells were detected by enzyme-linked immunosorbent assay (ELISA). Flow cytometry was used to evaluate the frequency of IL-22–producing CD4+ T cells. IL-22 mRNA from erythema nodosum skin lesions was examined using real time quantitative RT-PCR. Results BD patients with active uveitis showed a significantly higher expression of IL-22 in the supernatants of stimulated PBMCs and CD4+T cells compared with BD patients without active uveitis and normal controls. An increased frequency of IL-22-producing CD4+T cells was also found in BD patients with active uveitis. IL-22 mRNA expression was elevated in erythema nodosum skin lesions. In BD patients, a high IL-22 level in the supernatant of stimulated PBMCs correlated with the presence of retinal vasculitis and erythema nodosum. Conclusions IL-22 was associated with disease activity in BD and correlated with the presence of small vessel inflammation, suggesting that it may be involved in its pathogenesis.

Upregulation of interleukin 21 and promotion of interleukin 17 production in chronic or recurrent Vogt-Koyanagi-Harada disease.

OBJECTIVES To analyze the expression and potential role of interleukin (IL) 21 in the pathogenesis of Vogt-Koyanagi-Harada (VKH) disease. METHODS Blood samples were obtained from patients with VKH disease and from healthy control subjects. Serum IL-21 level and IL-21 messenger RNA (mRNA) expression by peripheral blood mononuclear cells (PBMCs) were determined by enzyme-linked immunosorbent assay and by reverse transcriptase-polymerase chain reaction, respectively. Interleukin 17 and interferon γ levels in the supernatants of PBMCs and CD4(+) T cells cultured with anti-CD3 and anti-CD28 antibodies in the presence or absence of recombinant IL-21 were detected by enzyme-linked immunosorbent assay. RESULTS The results showed a significantly increased serum IL-21 level, as well as higher IL-21 mRNA expression by PBMCs, in patients having chronic or recurrent active VKH disease compared with patients having inactive VKH disease and with controls. In vitro experiments showed that recombinant IL-21 significantly increased IL-17 production by PBMCs and by CD4(+) T cells from patients and from controls. However, recombinant IL-21 did not affect interferon γ expression by PBMCs or by CD4(+) T cells. CONCLUSION Interleukin 21 may be involved in the pathogenesis of chronic or recurrent VKH disease, possibly by promoting IL-17 secretion. CLINICAL RELEVANCE Findings from the present study suggest that IL-21 may be a potential target in the development of therapy for VKH disease.

Activation of liver X receptor alleviates ocular inflammation in experimental autoimmune uveitis.

PURPOSE To investigate whether a synthetic LXR agonist TO901317 (TO90) ameliorates ocular inflammation in a mouse model of experimental autoimmune uveitis (EAU) and to explore its underlying mechanism. METHODS EAU was induced with subcutaneous injection of IRBP161-180 peptide (SGIPYIISYLHPGNTILHVD) in B10.RIII mice. TO90 (50 mg/kg/d) or vehicle was administrated orally for successive 16 days or 8 days as prevention or effector phase, respectively. The severity of EAU was evaluated with clinical and histological scores. The levels of LXRs, NF-κB subunit p65, and an LXR target gene ABCA1 in the retina were detected with real-time PCR and Western blotting. The expressions of proinflammatory genes, including TNF-α, IL-1β, IL-6, MCP-1, IFN-γ, and IL-17, were detected by real-time PCR. IRBP-specific lymphocyte proliferation was detected by MTT. Intracellular IFN-γ and IL-17 in CD4(+) T cells were measured by flow cytometry. RESULTS We found both LXRα and LXRβ were expressed in mouse retina. After administering TO90 orally to B10.RIII mice, the expression of LXRα but not LXRβ was upregulated in the naïve mice. Compared with naïve mice, LXRα expression was increased in vehicle and TO90-treated EAU mice, but the LXRβ expression was unchanged. The protein level of ABCA1 was enhanced in TO90-treated naïve and EAU mice but was unchanged in vehicle-treated EAU mice, suggesting activation of LXRα by TO90 is ligand dependent. TO90-mediated activation of LXRα improved the clinical and morphological scores in EAU mice. Meanwhile, activation of LXRα decreased the expressions of proinflammatory cytokines, including TNF-α, IL-1β, IL-6, MCP-1, IFN-γ, and IL-17 in the retina. TO90 treatment inhibited IRBP-specific immune responses. The proportions of Th1 and Th17 expressing IFN-γ and IL-17 were reduced in TO90-treated EAU mice in both prevention and effector phases. Furthermore, TO90 significantly downregulated the expressions of an NF-κB subunit p65 at the protein and mRNA levels. CONCLUSIONS TO90 activates LXRα and potently attenuates ocular inflammation in EAU. Alleviation of ocular inflammation could partially result from inhibition of the NF-κB signaling pathway. TO90 reduces IFN-γ and IL-17 expression in both prevention and treatment scenarios. Our data suggest that the LXR agonist may become a novel class of therapeutic agent for autoimmune uveitis.

Activation of the aryl hydrocarbon receptor affects activation and function of human monocyte-derived dendritic cells

Aryl hydrocarbon receptor (AhR) is well known for mediating the toxic effects of dioxin‐containing pollutants, but has also been shown to be involved in the natural regulation of the immune response. In this study, we investigated the effect of AhR activation by its endogenous ligands 6‐formylindolo[3,2‐b]carbazole (FICZ) and 2‐(1′H‐indole‐3′‐carbonyl)‐thiazole‐4‐carboxylic acid methyl ester (ITE) on the differentiation, maturation and function of monocyte‐derived DCs in Behçets disease (BD) patients. In this study, we showed that AhR activation by FICZ and ITE down‐regulated the expression of co‐stimulatory molecules including human leucocyte antigen D‐related (HLA‐DR), CD80 and CD86, while it had no effect on the expression of CD83 and CD40 on DCs derived from BD patients and normal controls. Lipopolysaccharide (LPS)‐treated dendritic cells (DCs) from active BD patients showed a higher level of interleukin (IL)‐1β, IL‐6, IL‐23 and tumour necrosis factor (TNF)‐α production. FICZ or ITE significantly inhibited the production of IL‐1β, IL‐6, IL‐23 and TNF‐α, but induced IL‐10 production by DCs derived from active BD patients and normal controls. FICZ or ITE‐treated DCs significantly inhibited the T helper type 17 (Th17) and Th1 cell response. Activation of AhR either by FICZ or ITE inhibits DC differentiation, maturation and function. Further studies are needed to investigate whether manipulation of the AhR pathway may be used to treat BD or other autoimmune diseases.

Decreased interleukin 27 expression is associated with active uveitis in Behçet’s disease

InstructionInterleukin 27 (IL-27) is an important regulator of the proinflammatory T-cell response. In this study, we investigated its role in the pathogenesis of Behçet’s disease (BD).MethodsIL-27 mRNA in peripheral blood mononuclear cells (PBMCs) was examined by performing RT-PCRs. Cytokine levels in sera or supernatants of PBMCs, naïve CD4+ T cells, dendritic cells (DCs) and DC/T cells were determined by enzyme-linked immunosorbent assay. We used RNA interference in naïve CD4+ T cells to study the role of interferon regulatory factor 8 (IRF8) in the inhibitory effect of IL-27 on Th17 cell differentiation. Flow cytometry was used to evaluate the frequency of IL-17- and interferon γ–producing T cells.ResultsThe expression of IL-27p28 mRNA by PBMCs and IL-27 in the sera and supernatants of cultured PBMCs were markedly decreased in patients with active BD. A higher frequency of IL-17-producing CD4+ T (Th17) cells and increased IL-17 production under Th17 polarizing conditions were observed in patients with active BD. IL-27 significantly inhibited Th17 cell differentiation. Downregulation of IRF8 by RNA interference abrogated the suppressive effect of IL-27 on Th17 differentiation. IL-27 inhibited the production of IL-1β, IL-6 and IL-23, but promoted IL-10 production, by DCs. IL-27-treated DCs inhibited both the Th1 and Th17 cell responses.ConclusionsThe results of the present study suggest that a decreased IL-27 expression is associated with disease activity in BD patients. Low IL-27 expression may result in a higher Th1 and Th17 cell response and thereby promote the autoinflammatory reaction observed in BD. Manipulation of IL-27 may offer a new treatment modality for this disease.